Dishwashers and washing machines need three utilities to work: electricity, water and sewage. This makes them ideal appliances to install side by side, for example, in a kitchen where space is at a premium. Installing a dishwasher next to an existing washing machine isn't much different from installing a dishwasher by itself.
Run a wire for the dishwasher from where the dishwasher will be located to the main panel. The dishwasher should be on a dedicated circuit. Have a certified electrician perform this part. The dishwasher and washing machine shouldn't share the same circuit because they both use a lot of power, and if they are hooked up on the same circuit, it may cause an outage. Turn off the power to the circuit after it is installed.
Install a dual supply outlet on the hot water tap for the washing machine, if one isn't already there. This will split the hot water into two separate supplies: one for the washing machine and one for the dishwasher. Turn off the water supply at the main before you do this step.
Install a reducing valve on the outlet that you will be using for the dishwasher. This will allow you to hook up the smaller diameter water supply pipe for the dishwasher. Use plumber's tape to wrap the threads before you attach the supply hose.
Move the dishwasher to the area adjacent to its final location. Remove any packing materials and screws.
Connect the dishwasher drain line to the back of the machine. Secure the line in place with a hose clamp. Where you connect the outlet end depends on your set-up. If you are connecting it to the drain for the washing machine, fix it in place with wire. This option is tricky because you will have to place it inside the drain outlet, along with the washing machine drain hose. If the outlet is not large enough to fit both hoses, install a flange extension at the top. Your second choice is to run the drain to the sink trap or garbage disposal beneath the sink. Secure the line in place with a hose clamp.
Remove the bottom front panel from the dishwasher. Move the dishwasher to its final location.
Connect the electric wire to the terminals at the bottom of the dishwasher. Secure them in place with wire nuts. Wrap any bare wires with electrical tape.
Connect the water supply. Install the elbow joint on the front of the dishwasher. Wrap the thread in plumber's tape before screwing it into the machine. Connect the coupling from the water supply hose to the elbow joint. Tighten this hand tight at first, then an additional turn with the adjustable wrench.
Level the dishwasher by raising or lowering the legs as needed. Check with the torpedo level. Secure in place with brackets.
Test the dishwasher. Turn the water supply on, if you turned it off to install a dual supply valve. Turn on the power to the dishwasher circuit. Run an empty load in the dishwasher. Watch all of the pipes for leaks as the dishwasher runs through the cycle. Tighten any clamps or nuts if necessary.
Some municipalities require the presence of a device known as an "air gap." Check local building codes before you install. Don't run the dishwasher and the washing machine at the same time because this will quickly use up your home's hot water supply, resulting in dirty laundry and dishes.
Always use caution when working with water and electricity. If in doubt about any of the installation steps, consult a professional.